Cracking the sunroof open a bit (flip up mode) might allow a chimney effect to let the condensate out.
I suspect I don't need to mention this, but whatever you do, don't run the engine to keep warm. I found a gentleman (deceased) near Silverton while hunting, who tried that in an '81 Corolla. I wouldn't really wish that experience (of finding such a thing) on anyone. He'd been in the car for 3 weeks when I came across it.
Colo Springs, CO